Now a days the work is being done by hiring the space and resources from the cloud providers in order to do work effectively and less costly. This paper describes the cloud, its challenges, evolution, attacks along with the approaches required to handle data on cloud. The practice of using a network of remote servers hosted on the Internet to store, manage, and process data, rather than a local server or a personal computer. The need of this review paper is to provide the awareness of the current emerging technology which saves the cost of users.